96 corvette stalls when hot
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 801
Likes: 17
From: Middletown Delaware
96 corvette stalls when hot
96 when hot surges and stalls at 2000 rpm. If you catch it before it stalls it will idle. After it stalls it will restart and not stall again entill next day when it goes thru the same cycle. I would like to read opti low res and high res signals. Can this be done on a scanner or do i need an oscilloscope. There are no codes, replaced icm, coil, optispark. map, tps. iac. fuel filter. cleaned throttle body. all four 02 sensors. new battery fuel pressure good and steady during failure.
Last edited by Dave Witman; Jul 6, 2019 at 02:59 PM.
Le Mans Master
Joined: Sep 2013
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From: near the thumb in the mitten
O scope required to watch Opti resolution pattern. Scanner with snap shot function catching event possibly could show what is dropping out. Alot of new parts all related to this condition?
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 801
Likes: 17
From: Middletown Delaware
Ok little update got it to fail as usual but this time it was hard to start managed to get a noid light on and i have no injector pulses. Unfortunately problem cleared again before i could check for spark. I wish this would just fail so i could find the cause.
Le Mans Master
Joined: Sep 2013
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From: near the thumb in the mitten
Codes? Opti work different than HEI. Opti sends signal to PCM. PCM then sends signal to ICM for spark. PCM uses only Opti reference for injectors. Crank sensor is more for misfire ID protocol it's used with OBD2.
Le Mans Master
Joined: Aug 2015
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From: St. Charles MO
Then I would guess that it's not the opti, since the tach gets it's signal directly from the opti sensor. Did you put the noid light on both banks of injectors? The PCM has two amplifiers (I think that's what they're called?) for the injector signals - one for each bank. If side is firing and the other isn't during these failures, then maybe it's that part of the PCM.
Le Mans Master
Joined: Sep 2013
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From: near the thumb in the mitten
Full size uses same PCM so used PCM programmed to your car could be reasonable. Collecting Mitsubishi Opti sensors off wrecks could also be worthwhile. Since you are shopping for PCM. When hard to start afterwards what did tach do? IDK I would want to experience hard start atleast one more time with a scanner, before guessing. If Opti just turns off sending no signals, engine just turns off no codes.
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Le Mans Master
Joined: Aug 2015
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From: St. Charles MO
There is both a hi-res and low-res signal from the opti sensor. Check for both. However, if only the hi-res were out the car would continue to run, just not quite as well (but a lot better than sputtering and barely running or stalling frequently). If the low-res were out, I believe that would kill your tach signal. It's worth checking though.
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 801
Likes: 17
From: Middletown Delaware
ok ran 96 again today oscilloscope connected at low res signal of opti at the plug on the side of the fuel rail. I did loose signal as engine stalled an had erratic signal or spikes before stall. Also would not restart and i have no noid light signals on both sides. after a few minutes would start and shut down then would start and run like nothing was wrong... learned from previous owner that opti was replaced about 3 months ago its a cardone. ugg Any help?
Le Mans Master
Joined: Aug 2015
Posts: 6,091
Likes: 1,972
From: St. Charles MO
ok ran 96 again today oscilloscope connected at low res signal of opti at the plug on the side of the fuel rail. I did loose signal as engine stalled an had erratic signal or spikes before stall. Also would not restart and i have no noid light signals on both sides. after a few minutes would start and shut down then would start and run like nothing was wrong... learned from previous owner that opti was replaced about 3 months ago its a cardone. ugg Any help?
Le Mans Master
Joined: Sep 2013
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From: near the thumb in the mitten
OEM " Mitsubishi" optical sensor can easily be removed from GEN2 Opti. Pick n pull shopping wrecked full size. LT1 cars. Wrecks figuring they were useable prior to crash. The aftermarket housing and bearing will probably be ok.